ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
213 
BOTANY. 
A. GENERAL, including the Anatomy and Physiology 
of the Phanerogamia. 
a. Anatomy. 
(1) Cell-Structure and Protoplasm. 
Influence of Light on Cell-Division.* — Herr W. Lohmann has made 
experiments relative to the influence of intense light on Saccharomyces 
cerevisise and other yeasts. As source of light, a 15-ampere arc lamp and 
direct sunlight were used. Pure cultivations equally disseminated in 
wort-gelatin were exposed to the light, and after a certain exposure the 
newly formed cells were counted. From a great number of countings 
it was found that strong electric light exerted an inhibitory influence on 
cell-division in S. cerevisise. Direct sunlight acted in a similar way. 
Heterotype Divisions in Lilium Martagon.t — According to Miss E. 
Bargant, there are two series of nuclear divisions in the life-history of 
Lilium Martagon which exhibit 12 chromosomes instead of 24, viz. : — 
I. Spermatogenesis. (1) First division of pollen-mother-cell nucleus ; 
(2) second division of pollen-mother-cell nucleus ; (3) division of pollen- 
grain nucleus into vegetative and generative nuclei ; (4) division of 
generative nucleus in pollen-tube. II. Oogenesis. (1) Division of 
primary embryo-sac nucleus into micropylar and chalazal nuclei ; 
(2) division of micropylar daughter-nucleus; (3) division of both 
daughter-nuclei of micropylar nucleus. The second and third divisions 
in both series are precisely similar to vegetative nuclear divisions, except 
in possessing only half the number of chromosomes ; they are called 
homotype. The first nuclear division on either side is termed lieterotype , 
because the process of karyokinesis differs from that of the vegetative 
nucleus. The chief points which distinguish it are : — (1) The resting 
nucleus, after some increase in size, passes into a contracted state called 
synapsis ; (2) the chromatic ribbon of the spirem is not homogeneous, 
but is composed of an erythrophilous ribbon bearing a double row of 
cyanophilous dots; (3) longitudinal fission appears in the spirem ribbon 
before its division into chromosomes ; (4) a second longitudinal fission 
appears in each segment of the immature chromosomes ; (5) the segments 
•of each chromosome are tightly twisted on each other, and separate from 
near the middle or from either end; the chromosomes of the diaster 
stage are usually V-shaped. 
Formation of the Endosperm in Leucojum-J — Dr. L. Buscalioni 
records some anomalous instances of karyokinetic division of the nucleus 
in the formation of the endosperm in Leucojum vernim. During mitosis 
he has constantly observed, at the poles of the secondary nuclei or at the 
sides of the equatorial disc, a protoplasmic cord strongly stainable by 
haematoxylin, which advances more or less towards the periphery of the 
* Inaug.-Diss. Rostock, 1896. See Centralbl. Bakt. u. Par., 2 te Abt., ii. (1S96) 
_pp. 797-8. 
t Kep. 66th Meeting Brit. Ass., 1896, p. 1021. Cf. this Journal, 1896, p. 640. 
X Atti R. Aecad. Lincei, vi. (1897) pp. 187-8. 
